Airway eosinophilia in remission and progression of asthma: Accumulation with a fast decline of FEV₁

Background: As it is unknown whether complete asthma remission or progression of asthma is associated with airway inflammation and remodeling, we assessed these characteristics in bronchial biopsies of relevant subsets of asthma patients. Methods: Sputum and bronchial biopsies were obtained from asthma patients in remission (PC₂₀ histamine > 32 mg/ml, PC ₂₀ AMP > 320 mg/ml) and from those with either a slow FEV ₁ decline (<30 ml/year) or fast decline (>30 ml/year). Inflammatory cells and mediators were determined in sputum, inflammatory cells and aspects of airway remodeling in bronchial biopsies. Results: Asthmatics in remission and asthma patients with a slow FEV₁ decline had a similar extent of airway inflammation and remodeling in sputum and bronchial biopsies. Asthma patients with a fast FEV₁ decline had high sputum eosinophil numbers. Moreover, FEV₁ decline (ml/year) correlated with sputum eosinophil numbers (Rs = 0.51, p = 0.003) and ECP levels (Rs = 0.57, p = 0.001). Airway remodeling, i.e. basement membrane thickness, correlated with sputum eosinophils (Rs = 0.69, p < 0.001), sputum ECP (Rs = 0.46, p = 0.018) and airway wall eosinophil numbers (Rs = 0.49, p = 0.002). Conclusions: Asthma, even when in remission, is accompanied by airway inflammation and remodeling. Data suggest that eosinophils are important in a subset of asthma patients by association to accelerated FEV₁ decline and change of basement membrane thickness.